The present invention relates to a system for sensing the position of an object movable rotationally, rectilinearly or in some other way, by producing and processing one or more signals varying in accordance with displacement of the object.
Japanese Patent provisional publication No. 57-149914 discloses one conventional example of such a position sensing system using a so-called incremental rotary encoder (as shown in FIGS. 6 and 7). However, this system is not accurate especially when the direction of movement of the object alternates frequently between forward and backward directions or between clockwise and counterclockwise directions.